Add better `inspect` output for ExampleGroup

Pull Request for #1590 

The only problem I ran into was that the syntax error in the after hook test produces error output while running the spec (the test still passes).

> An error occurred in an `after(:context)` hook.
>   NoMethodError: undefined method `expcts' for #<RSpec::ExampleGroups::SomeClass_3 after(:context) hook>

This is definitely not ideal because it could distract from problems with "real" after hooks. The only two options I could up with were: 1) remove the test, or 2) add a way to suppress that error. I'm interested in your thoughts on the best way to handle this.
I think it'd prefer that this expectation was stronger, including more of the full `inspect` output, given that we are formatting it a specific way and want the doc string and line number to show up in specific places.